Apparatus for technical drawing

ABSTRACT

1,102,922. Draughting machines. MINISTERSTWO SZKOLNICTWA WYZSZEGO. Feb. 12, 1965 [Feb. 25, 1964], No.6285/65. Heading G1X. [Also in Division A4] A drawing board easel Fig. 6, comprises a base 10, a frame 9 pivotally mounted on the base, and a support member 11 hinged to the frame at 13 and selectively engageable in catches 14 in the base 10. A drawing board (1, Fig. 1), has parallel guide bars (2) with wedge-shaped locking members (4, Fig. 4). The locking members are normally spring-biased to engage the side members of the frame 9, and can be released by operating levers (8). The board is provided with a straight edge (17, Fig. 7), with a cord-pulley mechanism giving parallel motion.

Oct. 21, 1969 M. J. GRZYWACZ 3,473,491

APPARATUS FOR TECHNICAL DRAWING Filed Feb. 9, 1965 4 Sheets-Sheet l Marian Jan Grzgwacz [.VVEXTOR Attorney Oct. 21, 1969 M. J. GRZYWACZ APPARATUS FOR TECHNICAL DRAWING 4 Sheets-Sheet 2 Filed Feb. 9, 1965 FIG. 4

Marian Jan Grzywacz /.\'V5\'TOR Oct. 21, 1969 M. J. GRZYWACZ 3,473,491

APPARATUS FOR TECHNICAL DRAWING Filed Feb. 9, 1965 4 Sheets-Sheet 3 Marian Jan Grzywacz 1x VENTOR.

Attorney 1969 M. J. GRZYWACZ APPARATUS FOR TECHNICAL DRAWING 4 Sheets-Sheet Filed Feb.

Marian Jan Grzgwacz 1.\" WEN-"TOR Attorney 3,473,491 APPARATUS FOR TECHNICAL DRAWING Marian Jan Grzywacz, Ul. Lazurowa 225, Warsaw 49, Poland Filed Feb. 9, 1965, Ser. No. 431,276 Claims priority, application Poland, Feb. 25, 1964,

Int. Cl. A47f /12 11.5. Cl. 108-6 6 Claims ABSTRACT OF THE DISCLOSURE Drafting appliance with a tiltable board rest having rails slidably engaged by a drawing board and means for locking the board in position on its rest at different elevations.

My present invention relates to an apparatus for technical drawing. The apparatus according to the invention is destined to enable the making of technical drawings in a comfortable position either sitting or standing, using an adjustable and at the same time slidable drawing board equipped with a ruler provided with an improved cordpulley mechanims.

Hitherto the draftsman was forced to use expensive, heavy and bulky drawing tables, with adjustable drawing boards provided with drawing tools. The drawing was mostly done in a standing position. Because of many joints and detrimental bending moments in component parts, these tables lost their precision after a certain time.

In school rooms and drawing otfices of technical colleges, drawings were made in an inconvenient and very tiresome semi-inclined position, using horizontal drawing boards fixed to tables. Conventional T-squares were used or rulers with ordinary cord-pulley mechanisms dropping under their own weight upon inclination of the boards.

The standard T-square was unhandy and trouble-some in use, requiring a continuous holding of its cross-member with the left hand thereby complicating as well as slowing the work of drawing.

Rulers equipped with cord-pulley mechanisms were seldom used by draftsmen because no part of the mechanism assured the parallel movement of the ruler or counteracted its downward movement by its own weight on sloping drawing tables.

A drafting appliance according to the invention avoids the aforementioned drawbacks and, particularly when equipped with a ruler comprising an improved cordpulley mechanism instead of a conventional T-square is more exact in use and contributes greatly to the draftsmans comfort.

This drawing apparatus according to the invention is first of all light in weight and inexpensive, being almost times cheaper and far lighter in comparison with hitherto used drawing tables. It is stable and simply constructed, easy in setting up and manipulation besides being comfortable in use; it can be put on a table, cabinet or the like; it can also be affixed to the wall; it can be easily stored because, when folded, it takes up little room.

In the accompanying drawing illustrating an embodiment of the invention:

FIG. 1 shows the reverse side of a drawing board with locks attached to it in accordance with my invention;

FIG. 2 shows a plan view of the same drawing board;

FIG. 3 is an enlarged view of the circled area of FIG. 1;

FIG. 4 is a side view of the lock, taken on the line IV-IV of FIG. 3;

FIG. 5 is another view of the lock taken on the line V-V of FIG. 3;

FIG. 6 shows a perspective view of the supporting structure for the drawing board of FIG. 1;

nitcd States Patent 0 3,473,491 Patented Oct. 21, 1969 "Ice FIG. 7 shows schematically an improved cord-pulley mechanism for a ruler on the board; and

FIG. 8 is a fragmentary perspective view of the board of FIG. 1.

The illustrated drafting appliance according to the invention is composed of three units.

The first unit comprises two locks aflixed to the reverse side of a drawing board 1, each locking including a wedge 4 constantly subject to the pressure of a spring 6, and a lever 8 by means of which the wedge 4 can be shifted in relation to a reaction plate 7 fixed to a supporting block 3, which is rigidly connected wtih the board 1 by a respective bar 2.

The second unit is a supporting structure comprising a board rest in the form of a frame 20 rotatable about a horizontal axis 12 on a base 10 and braced by a supporting frame 11 in a selected angular position; the supporting frame 11 has one side mounted on hinges 13 of a cross-bar 19 of frame 20 and has its opposite side engaged in corresponding notches 14 on base 10.

Notches 14 on base 10 cut out in an almost perpendicular inclination to the plane of the supporting frame 11, ensure a stable retention of the tiltable board rest 20 in relation to the base 10 in any position of inclination of the drawing board sliding on the side members or rails 9 of frame 20 above or below the axis of rotation 12. The locks and the supporting structure including bracing means 11 enable a firm stabilization of the drawing board 1 on rails 9 in a position most convenient for drawing. The angle of inclination of rails with the drawing board mounted on them, in relation to a horizontal plane, may vary from 0 to When both locks 38 are simultane ously released, the drawing board 1 can be shifted along rails 9 for immobilization at different elevations. The spacing of the bars 2, which bracket the rails 9, corresponds to the distance between the faces of these rails as indicated in FIGS. 1 and 6.

The third unit is a ruler 21 provided wtih an improved cord-pulley (FIG. 7). The improvement consists in the application of three new component parts to a known cord-pulley mechanism: a reversibly acting cord tightener 15, a clamp 16 fixing the cord on the drawing board 1, and a clamp 17 fixing the cord on the ruler at the point of crossover of the two courses of cord 22.

One end of the cord 22 is permanently fixed at 18 to the board. Cord tightener 15 is fixed to the drawing board and connected to the other end of the cord to create sufficient friction on the pulleys of the mechanism to counteract a free downward movement of the ruler at different inclinations of the drawing board.

By means of clamp 16 pressing the cord 22 onto the board 1, a precise parallelism of successive positions of the traveling ruler is ensured in spite of the inclination of the drawing board; the chosen positions of the ruler may vary within the limits of about 30 in relation to the longer drawing-board edges.

By means of clamp 17 pressing the crossed cord onto the ruler, parallelism is achieved in any position on the drawing-board, thus being very useful to the drattsman.

I claim:

1. A drafting appliance comprising a base, a board rest tiltably mounted on said base for pivotal movement about a horizontal axis, bracing means for selectively securing said board rest in a plurality of angular positions relative to said base, a drawing board having guide means coacting with said board rest for sliding motion thereon transverse to said axis, self-engaging locking means on said board for selectively arresting same at different elevations on said board rest upon manual disengagement of the locking means and the manual positioning of the board with respect to said rest along said guide means, a

straight edge mounted on said board for movement therealong, and a cord-and-pulley arrangement for guiding said straight edge parallel to itself, said arrangement including a tensioned cord anchored to said board at locations spaced apart generally in the direction of the major dimension of said straight edge, pulley means on said straight edge and on said board engaged by said cord, and blocking means on said board, engageable with said cord to limit movement of same along said board, said bracing means comprising a supporting frame hinged to said board rest, said base being provided with notches selectively engageable by said frame in respective angular positions thereof and extending substantially at right angles to the plane of said frame in said respective angular positions.

2. An appliance as defined in claim 1 wherein said board rest is provided with a rail transverse to said axis and slidably engaged by said guide means, said locking means including a reaction member fixed to the reverse side of said board and overlying said rail, a wedge interposed between said rail and said member, and handle means for displacing said wedge along said rail with reference to said member between a clamping position and an unclamping position.

3. A drafting appliance comprising a base, a board rest tiltably mounted on said base for pivotal movement about a horizontal axis, bracing means for selectively securing said board rest in a plurality of angular positions relative to said base, a drawing board having guide means coacting with said board rest for sliding motion thereon transverse to said axis, and locking means on said board for selectively arresting same at different elevations on said board rest, said board rest being provided with a rail transverse to said axis and slidably engaged by said guide means, said locking means including a reaction member fixed t the reverse side of said board and overlying said rail, a wedge interposed between said rail and said member, handle means for displacing said wedge along said rail with reference to said member between a clamping position and an unclamping position, and a spring urging said wedge into said clamping position.

4. An appliance as defined in claim 3 wherein said bracing means comprises a supporting frame hinged to said board rest, said base being provided with notches selectively engageably by said frame in respective angular positions thereof and extending substantially at right angles to the plane of said frame in said respective angular positions.

5. A drafting appliance comprising a base for pivotal movement about a horizontal axis, bracing means for selectively securing said board rest in a plurality of angular positions relative to said base, a drawing board having guide means coacting with said board rest for sliding motion thereon transverse to said axis, and locking means on said board for selectively arresting same at ditferent elevations on said board rest, said board rest being provided with a pair of parallel rails transverse to said axis and slidably engaged by said guide means, said locking means including a pair of reaction members fixed to the reverse side of said board and respectively overlying said rails, a pair of wedges respectively interposed between said rails and said members, and handle means for displacing said wedges along said rails with reference to said members between a clamping position and an unclamping position.

6. An appliance as defined in claim 5 wherein said bracing means comprises a supporting frame hinged to said board rest, said base being provided with notches selectively engageable by said frame in respective angular positions thereof and extending substantially at right angles to the plane of said frame in said respective angular positions.

References Cited UNITED STATES PATENTS 2,194,889 3/1940 De Lisle 1085 2,593,364 4/1952 Thompson 1087 1,270,609 6/1918 Ezra 33-80 X 2,162,264 6/1939 Linsner 3380 3,082,535 3/ 1963 Cardinell 3380 BOBBY R. GAY, Primary Examiner G. O. FINCH, Assistant Examiner US. Cl. X.R. 108-50 

